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Engine wiring diagrams please?

Tiny
VERMY1128
  • MEMBER
  • 2005 BMW 745
  • 4.4L
  • V8
  • 2WD
  • AUTOMATIC
  • 93,000 MILES
Car will crank but not start, tested crankshaft position sensor and it failed, replaced sensor and still no start didn't test new sensor before installing but did after car wouldn't start and it failed the test, tested a new sensor before installing and it was good but vehicle failed to start. Removed sensor tested it and all three sensors have the same problem, no continuity between the signal and ground probes of the sensor. I'm sorry it is a three wire sensor. Do my question is, what would cause this to happen?
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Wednesday, January 16th, 2019 AT 7:25 AM

3 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
The brown wire is digital ground, the yellow wire should be the 5 volt supply and the black wire the reference to the PCM. here is the engine wiring diagrams so you can see how the system works with a guide to help you test the wiring:

https://www.2carpros.com/articles/how-to-check-wiring

It sounds like the sensors are good btw. Have you checked the DME relays? Can you tell me if you have power at terminal 7 and 8 on the PCM?

Lets run the codes as well.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Check out the diagrams (below). Please let us know what happens.
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Thursday, January 17th, 2019 AT 11:50 AM
Tiny
VERMY1128
  • MEMBER
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Hello Ken, and thank you for your quick reply and thanks for your help. I hope you get me through this, check the brown, yellow and black wires for continuity and shorts they were fine but the yellow supply wire is supplying battery voltage (12.4) and the black wire has no ground? The wiring diagrams would have been extremely helpful had they been legible (I think maybe it's my computer) and I didn't know the DME had relays will check them when I locate them.
I checked the PCM and there is battery voltage (12.4) at terminal 8 with the wiring harness disconnected but when it is connected there is only 0.8 volts there and no voltage at terminal 7 at all. I did run the code before and wrote them down but the paper has been misplaced and now unable to run them and there were three codes associated with the Crankshaft Position Sensor and the only two I remember is p1715 and p0356.

And again thanks for the help!
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Friday, January 18th, 2019 AT 2:10 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
To read the wiring diagrams you click on the image and it enlarges. Terminal #7 is an injector trigger so it won't have voltage. The code suggests a sensor wiring or PCM issue. Try the sensor check the wires and if that doesn't work replace the PCM. Here is the location:
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Saturday, January 19th, 2019 AT 10:56 AM

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